The Influence of Physical Soil Properties on Erosion Resistance of Sandy-Clays: Insights from Jet Erosion Tests

The erosional resistance of soils dominantly influences the safety and serviceability of hydro-geotechnical structures such as dikes, dams, canals, riverbanks, piers, etc. In the absence of detailed erosion testing, it is prudent to have an educated estimate of erosion resistance based on simple physical/mechanical properties of soils. This study systematically investigates the interrelation between soil physical properties and erosion propensity of clay-sand mixed soils. Jet erosion tests were performed on carefully controlled, laboratory-substantiated mixtures of a clay soil with different amounts (10 %, 20 %, 30 %, 40 %, and 50 %) of silica sand, and erosion parameters, that is, critical shear stress (τc) and erodibility/detachment coefficient (kd) were measured. Experimental findings confirmed that the amount of fines, clay content, plasticity index, and compaction water content positively increased the erosion resistance, whereas the dry density and unconfined compressive strength were not directly influential in erodibility. Moreover, results suggested that the soil fabric significantly influenced erosional behavior insofar as the soil reflected a sharp drop in erosion resistance upon becoming sand dominated. Regarding practical applications, seven equations available in the literature for prediction of critical shear stress (τc) were compared with test measurements, and their accuracies were assessed.